A Capped Trigonal Prismatic Cadmium Complex With Tetra- and Tridentate Ligands: Bis(triethanolamine)-K3N,O,O′K4N,O,O′,O″-Cadmium(II) Squarate Monohydrate

Abstract

In the crystal structure of the title compound, [Cd(C<inf>6</inf>H <inf>15</inf>-NO<inf>3</inf>)<inf>2</inf>](C<inf>4</inf>O<inf>4</inf>) ·H<inf>2</inf>O, a supramolecular structure is observed. The asymmetric unit consists of one unit of the cationic Cd complex, one water molecule and two half-squarate anions, each sitting on a crystallographic inversion center. The different coordinations of the two triethanolamine (TEA) ligands results in an unusual example of coordination number seven for the CdII ion. Both TEA ligands coordinate to the CdII ion, forming a distorted monocapped trigonal prismatic geometry with approximate C<inf>2v</inf> symmetry. One of the TEA ligands acts as an N,O,O′-tridentate ligand, whereas the other behaves as an N,O,O′,O″-tetradentate donor. The anions and cations are linked to one another by hydrogen bonds between hydroxy H atoms of the TEA ligands and squarate O atoms. The crystal structure is stabilized by O-H⋯O hydrogen bonds between the unligated water molecule and a squarate O atom, together with a weak π-ring interaction between the ethylene group of a TEA ligand and a squarate anion.